Within such a fluid circuit, such a thermostatic valve is used to regulate the flow of a fluid, i.e., to distribute this fluid in different pathways of the circuit, based on the temperature of this fluid. These valves are said to be thermostatic inasmuch as the movement of their inner seal relative to a seat associated with the housing of the valve is controlled by a thermostatic element, i.e., an element that comprises a body, containing a thermodilatable material, and a piston, submerged in this thermodilatable material, the body and the piston being movable relative to one another in translation along the longitudinal axis of the piston, while either the body or the piston is, during use, fixedly connected to the housing of the valve. FR-A-2,961,917, FR-A-2,919,704, FR-A-2,987,095 and WO-A-2010/012950 provide examples of such thermostatic valves.
This being recalled, it is known to authorize a slight flow of the fluid, typically described as an leak, through the stopper, in particular when the latter is in contact with the seat of the housing and closes the corresponding fluid flow passage. In this way, even when the stopper is in the closed position, a small quantity of fluid continues to flow through the stopper, which prevents arriving at an excessively high pressure differential on either side of the stopper, which could disrupt the operation of the valve, for example by causing pressure surges when the stopper is commanded to move away from the closed position. Of course, this controlled leak must remain low to maintain the expected regulation. In practice, various leak solutions, integrated into the stoppers of the existing thermostatic valves, are widespread and proven.
More recently, DE-U-20 2010 017 837 proposed integrating a leak of this type into a stopper made in a single piece of plastic. While the piston of the thermostatic element is fixedly connected to the valve housing, the body of this thermostatic element is received inside the stopper, by arranging, between the latter and the body of the thermostatic element, three separate passages for the free flow of the fluid, which occupy three separate angular portions around the body of the thermostatic element. The leak is thus channeled along the body of the thermostatic element, while being distributed into three streams locally sweeping the body of the thermostatic element. However, this solution proves restrictive and costly to implement, since it has a limited mechanical strength, in particular over the long term, and has a frozen design inasmuch as any change to the outer diameter of the stopper and/or the size of the thermostatic element requires completely resizing the stopper.